This invention relates generally to the field of refractive surgery and, more particularly, to microkeratomes used for performing laser refractive surgery.
The human eye in its simplest terms functions to provide vision by transmitting light through a clear outer portion called the cornea, and focusing the image by way of a crystalline lens onto a retina. The quality of the focused image depends on many factors including the size and shape of the eye, and the transparency of the cornea and the lens.
The optical power of the eye is determined by the optical power of the cornea and the crystalline lens. In the normal, healthy eye, sharp images are formed on the retina (emmetropia). In many eyes, images are either formed in front of the retina because the eye is abnormally long (axial myopia), or formed in back of the retina because the eye is abnormally short (axial hyperopia). The cornea also may be asymmetric or toric, resulting in an uncompensated cylindrical refractive error referred to as corneal astigmatism. In addition, due to age-related reduction in lens accommodation, the eye may become presbyopic resulting in the need for a bifocal or multifocal correction device.
In the past, axial myopia, axial hyperopia and corneal astigmatism generally have been corrected by spectacles or contact lenses, but there are several refractive surgical procedures that have been investigated and used since 1949. Jose Barraquer, M.D. investigated a procedure called keratomileusis that reshaped the cornea using a microkeratome and a cryolathe. This procedure was never widely accepted by surgeons. Another procedure that has gained widespread acceptance is radial and/or transverse incisional keratotomy (RK or AK, respectively). In the 1990s, the use of photoablative lasers to reshape the surface of the cornea (photorefractive keratectomy or PRK) or for mid-stromal photoablation (Laser-Assisted In Situ Keratomileusis or LASIK) have been approved by regulatory authorities in the U.S. and other countries. Recently, a new version of PRK called Laser Epithelial Keratomileusis (LASEK) has been developed wherein the epithelial layer is soaked in alcohol so as to release it from Bowman""s Membrane and the epithelial layer is non-destructively rolled aside and the underlying stromal tissue is ablated in a manner similar to PRK. This procedure does not always allow for the smooth removal of the epithelial layer in a single sheet. In addition, alcohol is toxic to corneal tissue.
Accordingly, a need continues to exist for a device and method for the safe, consistent removal of the epithelial layer and Basement Membrane during a laser refractive surgical procedure.
The present invention improves upon the prior art by providing a microkeratome blade for use for the removal of the epithelial layer and underlying Basement Membrane while leaving a smooth and undisturbed Bowman""s Membrane in preparation for a laser refractive surgical procedure. The blade is capable of cutting through the epithelial layer and Basement Membrane, but not capable of cutting through Bowman""s Membrane.
Accordingly, one objective of the present invention is to provide a safe and non-toxic method for the removal of the epithelial layer and underlying Basement Membrane in preparation for a laser refractive surgical procedure.
Another objective of the present invention is to provide a method for the removal of the epithelial layer in preparation for a laser refractive surgical procedure without the use of toxic chemicals.
Another objective of the present invention is to provide a device that provides the safe and non-toxic method for the removal of the epithelial layer and underlying Basement Membrane in preparation for a laser refractive surgical procedure.
Another objective of the present invention is to provide a microkeratome blade that provides the safe and non-toxic method for the removal of the epithelial layer and underlying Basement Membrane in preparation for a laser refractive surgical procedure.
These and other advantages and objectives of the present invention will become apparent from the detailed description and claims that follow.